Telephone receiver



Sept. 20, 1927.

1,643,104 D. R. WALLACE TELEPHONE RECEIVER Filed Nov. 16. 1923 gnvantoo Patented Sept. 20, 1927.

,"U'NIifw States .havin Romani) WALLACE, or JOPLIN, MIssoURI.

teniet erica.

Parent TELEPHONE RECEIVER.

f "Application filed November 16, 1923. 'Serial- No. 675,206.

v This invention relates to improvements in telephone receivers and more particularly tov that type. especially adaptedfor use v'with radio apparatus. l Y Y 4One ofr the objects of the present invention is`to` provide a receiver of the above general character known .as the watch case type' of simple" and practical construction and lwhich will be exceedingly'sensitive in use and operation.: l

v The receiver in question is provided with two pole pieces one of which is inside of the y other,tlie .inside pole piecepassing through YReiterring particularly to Figure 1 nu- Ineral .12 indicates a cup shaped casing made of insulating'material uponwhich is thrcaded theicap earpiece 13 l"also made of. insulating material. VvWithin the casing andv conf forming approximatelyto the inner dimensions. ofthe casingis-a cup shaped magnetic pole piece 6L that is fastened tothe casing by means of screws 30 secured through the base of the casing and threaded into the magnetic pole piece 6. The rimof the magnetic pole piecei6 iszbevelledto form a knife edge asshownv at 7 and lupon which rests the diaphragm 8, that is preferablymade thinner around its periphery than near its center to increase its iiexibility.' 1

Through the central portion of thebase of thereon by the pole of magnet 3. Uponthe outer end of magnet 3 there is member 22 rigidly afiixed thereto for adjusting the inner tip of the magnet 3 toward or away from the diaphragm 8. Threaded upon the mag! net 3 between the 'member 22 and the base ofthe pole piece 6 is a locking member 21 controlled by a lever 20 by which the magnet insulating material.

3 is fixed in any position inl-,which it' is placed by the rotation of member 22.V

Within the cup of magnetpole piece 6 there is located a magnetic shield llaiiixed to the base of the magnetic pole V,piece 6v by means of screws 31. The shieldy 11 surrounds the permanent magnet 3f to a point near its tip but suiiiciently removed from the dia.-` phragm 8 that the diaphragm will not strike the shield when vibrating at its maximum amplitude. yThe shield llis separated from the'permanent magnet 3 -by a small gapr32 to allow the free adjustment Iof magnet 3 toward and away from the diaphragm 8. The gap32 may or may not be filled with Upon the lcentral cylinder of shield 11 is wound the coil 10 which fis held in form by the base of shield 11 upon oneend and upon the other by a fibre or brass member 23. The terminals of coil 10 are soldered tol the threaded brass tubes 15 within. fibre blocks 16 mounted upon the base of pole piece 6.

.ln the fibre blocks 16, the magnetic pole piece 6, andcthe casing 12 are aligned holes 17, 27, and 18 through which the connections to the coil l0 are made. The terminals ofthe leads to the coil 10 are held in position by means of screws 14 within the threaded brass tubes 15 within the fibre blocks 16.

It will be seen that there is only one gap in the magnetic circuit of this receiver as compared to two gaps or breaks in the mag'- netic circuit of most other receivers. The magnetic lines of force from the permanent magnet 3 pass through the diaphragm and across the gap at the center. f As the attractionv of any magnet for its armature is in'direct yratio to ,the intensity of the field or to the number of lines of force that pass through it and as the number oflines of versely as to square of the distance intervening it will be clear that the magnetic pull for a diaphragm of this type of receiver will be four times that of a receiver having two gaps in its magnetic circuit.

The lines of force set up in ahe current flowing in a coil 10 and acting on a soft iron cylinder or sleeve 11 surrounding the pole 3 also follow the'magnetic circuit of the permanent ymagnet when the current is fiowing in one direction in the coil thus adding to the strength of the permanent magnet and as the current changes amplitude or reverses direction, its magnetic lines of force,

Uil

Vforce from amagnet to its armaturevary in llt being of opposite polarity will now attract nearly all of the lines of force from the center pole shielding the diaphragm and del others of the two pole type.

In Figure 3 the outside pole piece 24 acts as "a retainer for the receiver and an ear piece 25 is directly secured thereto. The shield may be eliminated here by using sort iron for the center pole piece 3 which is also adjustablyvmounted as indicated by the threads in part '24. 'A slot 26 permits the relative adjustment with respect to the diaphragm 8 as yand when desired. i

While Ivh'ave lillustrated only two of various possible vmodifieations it will, of cou-rse, be understood that others may be made without departing `from the invention.

What I claim is l. In 'a receiver of the character described, in combination, two pole pieces, lone inside of the other, the outer pole piece being provided with aknife edge and a diaphragm supported `from said knife edge.

2. In a receiver of Vthe character described, 4in combination, two concentrically disposed pole pieces, the outer pole having a knifeedged periphery and a diaphragm supported therefrom and held i-n place by the magnetism ofthe Ycenter pole piece.

3. -Ih a receiver 'of the character described, in combination, two concentrically disposed pole pieces, the 'outer pole piece having a knife-'edged lperiphery and a diaphragm supported therefrom held in place by the magnetism of the center pole piece and means whereby the center pole piece may be adjusted towards and from the diaphragm.

4. In a receiver 'of the character described, in combination, two Vconcentrically disposed :pole pieces, a one piece metal diaphragm gradually tapering Vtowards its periphery supported from the outer pole piece, said center pole piece being adjustably mounted in the outer pole piece and a lock nut for holding said pole piece in adjusted position.

5. In a receiver of the character described.

ing said central pole piece, acoil mounted 1 on said shield, a diaphragm, means foradjusting the central pole piece towards and from the diaphragm and a receiver case for said parts the ear piece of which tapers outwardly towards its aperture. Y Y

8. In a receiver of the character described, I

a cup-shaped outer pole piece, ,a centrally mounted pole piece coacting therewith and means associated therewith `for supportinga coil and adapted vto perform the functions of the aforesaid shield and center polepiece combined. i

9. In a receiver of the character described, in combination, an Vear pi'ece tapering outwardly towards its aperture in the center on its under side, a one-piece `metal diaphragm thinner near its outer edge, a knife-edge supportingthe same, two magnetized' vpole pieces,ione inside the other, the `outer pole piece 'supporting said diaphragm, a magnetic shield on one sideof the coil, a coil and means for mounting it on the magnetic shield, terminal connections for said coil, means for mounting the magnetic shield on the 4outer pole piece, means 'for'adju/sting land locking the outer pole piece in relation to the diaphragm `and means or mounting the complete assembly -i-n areceiver case.l c

signed at Brooklyn, N. Y.,y this ist. day" of Sept., 1923.

'DAVID RONALD WALLACE. 

